1. Field of the Invention
This invention relates to a method of connecting plural covered wires to each other.
2. Description of the Related Art
In an automobile as a transferring object, a wiring harness is provided to supply electric power of a battery to installed electronic devices, such as various lamps and motors, and send control signals of a control unit to the electronic devices. The wiring harness has plural covered wires, or the like. At least some of the plural wires comprising the wiring harness are required to connect to each other.
When connecting conductors of the covered wires to each other, firstly, the cover of the wire is removed at a connecting point. After that, the conductors are connected by welding, like resistance welding. Or, as another connection method, pressure contact or crimp contact with other conductive metal parts, different from the conductor, is used to connect the conductors of the covered wires to each other.
Methods of connecting covered wires mutually according to the prior art, as mentioned above, require removing the cover of covered wires. Consequently, the time and effort for performing the work operations increases. Further, using additional other metal parts makes the number of parts increase. Therefore, methods of connecting covered wires by prior art methods produce a cost increase.
This invention has been accomplished to overcome the above drawbacks and an object of this invention is to provide a method of connecting covered wires mutually which can avoid cost increasing.
In order to attain the objects, a method of connecting covered wires according to this invention is comprised of the steps of placing a covered wire on the other covered wires and welding conductors of the covered wires to each other by ultrasonic welding.
In the method of connecting covered wires, as mentioned above, the covers of each of the covered wires are adhered to each other by the above ultrasonic welding.
In each method of connecting covered wires, as mentioned above, one covered wire and the other covered wire are clamped by a chip and an anvil, correspondingly and mutually, of an ultrasonic welding machine and said chip is placed in straddling form on one covered wire and the covered wires are connected by ultrasonic welding.
Since the connection of the covered wires according to this invention is done by ultrasonic welding in the condition of placing a covered wire on other covered wires, removing the cover on the connection point of the covered wires is not required to connect covered wires to each other. Since the covered wires are ultrasonic welded mutually one upon another, other metallic parts different from the covered wires are not required to connect the covered wires to each other. The covered wire, which has a round cross section, is preferable. In case of the wire with a round cross section shape, the cover is removed securely from a gap between each conductor by ultrasonic welding. Therefore, the method can perform to connect each conductor securely without a need of removing the cover.
Advantageously, in the above method of connecting covered wires mutually according this invention, since the covers adhere to each other by ultrasonic welding, the mechanical strength of the point where the conductors are connected mutually can be improved. Further, since the covers adhere to each other, the conductors can be connected securely to each other without a need of removing the covers.
Advantageously, in the above method of connecting electric wires mutually according this invention, the chip of an ultrasonic machine is placed with straddling form on one covered wire. Therefore, the conductor of one covered wire, which the chip contacts, is pushed securely toward the conductor of the other covered wire and connecting conductors to each other can be done more securely. In this method of connecting electric wires, the chip may be formed either larger or smaller than the larger diameter of one covered wire which the chip contacts by ultrasonic welding or the other covered wire along the radius direction of the covered wire.
Preferably, in this method, the chip is formed in strip shape. When one covered wire and the other covered wire, as mentioned above, are disposed to cross each other one upon another, the cross section of the chip along the length of the covered wire may cross one of the covered wires to be contacted by ultrasonic welding and be along the length of the other.
In this condition of two covered wires crossing each other, the chip contacts one covered wire along the length of the covered wire and crosses the other covered wire. Then, the top of the chip dents one covered wire that the chip contacts. Therefore, the chip can press securely the conductor of one contacted covered wire toward the conductor of the other covered wire, and connect tightly the conductors to each other.
In the condition of placing one covered wire and other covered wire in parallel one upon another, the length of the strip shape chip on the cross section along the length direction of the covered wires is aligned preferably along the length of the covered wires which are placed in parallel one upon another. In this case, the thickness, perpendicular to the length of the chip on the cross section along the length direction of the covered wires, may be larger or smaller than the diameter of the covered wires.
The chip is placed with its length along the length direction of covered wires disposed parallel to each other, and stacked one on another. The top of the chip dents one covered wire that the chip contacts. Therefore, the chip can press securely the conductor of one contacted covered wire toward the conductor of the other covered wire, and connect tightly the conductors to each other.
As mentioned above, according to an aspect of this invention, covered conductors can be bonded to each other without need of removing the covers, since the covered wires are connected mutually by ultrasonic welding. Other metal parts, different from these covered wires, are not required to connect covered wires mutually since covered wires are connected mutually one upon another by ultrasonic welding. Therefore, the time, effort and number of parts for connecting the covered wires 2, 3 can be reduced and the cost also can be reduced.
According to another aspect of this invention, cost reduction for connecting covered wires mutually is not the only benefit, but mechanical strength at the connecting point of the covered wires can also be improved, since the covers are adhered to each other when connecting the wires by ultrasonic welding.
According to yet another aspect of this invention, a chip is located by saddles on one covered wire which is contacted by the chip in case of crossing covered wires one upon another to each other. Therefore, the chip pushes more securely a conductor positioned above one covered wire, contacted by the chip, toward a conductor of the other covered wire. Then, time, effort and the number of parts for connecting the covered wires 2, 3 are not only reduced but the conductors can be also bonded more tightly.